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PREMIS OWL. Sam Coppens Multimedia Lab Department of Electronics and Information Systems Faculty of Engineering Ghent University. Survey. Quick intro in semantic web Why PREMIS OWL? Design Example Conclusion. Intro Semantic Web. XML / XSD. Metadata in XML <author>
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PREMIS OWL Sam Coppens Multimedia Lab Department of Electronics and Information Systems Faculty of Engineering Ghent University
Survey • Quick intro in semantic web • Why PREMIS OWL? • Design • Example • Conclusion Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
Intro Semantic Web Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
XML / XSD Metadata in XML <author> <uri>page</uri> <name>Ora</name> </author> <document> <details> <uri>href="page"</uri> <author> <name>Ora</name> </author> </details> </document> <document href="page"> <author>Ora</author> </document> Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
XML / XSD XML problem: <x> <y>page</y> <z>Ora</z> </x> <x> <y> <z>href="page"</z> <v> <w>Ora</w> </v> </y> </x> ? ? ? <x href="page"> <y>Ora</y> </x> Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
XML / XSD ? Structure XML Schema ? meaning Tags ? ? ? ! Exchange Format Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
Semantic Web technologies • Technologies developed by the World Wide Web Consortium (W3C) • Goal: make the Web a universal medium for data, information and knowledge exchange • HTML, XML -> RDF, RDFS, OWL, … Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
RDF • RDF (Resource Description Framework) • Triples: subject – predicate – object • URI to identify resources • “The author of the note is Tim” • Serialisatie in XML: • <rdf:RDF xmlns:rdf=http://www.w3.org/1999/02/22-rdf-syntax-ns#> <Note rdf:about=http://www.example.org/#note> <hasAuthor rdf:resource="http://www.example.org/#Tim”/> </Note> </rdf:RDF> Note Tim hasAuthor Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
RDFS • RDF Schema • Standardised terms to describe concepts • Introduces classes and instances • Subclasses, subproperties • Hierarchy! Class Person ClassNote rdf:type rdf:type Note1 Tim hasAuthor Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
OWL • Web Ontology Language, W3C recommendation (2004) • Richer vocabulary • Defines advanced relations • Data-typing • Cardinality • Rich typing van properties • … • Example: • Reasoning! • complex ontologies Class Person ClassNote type type Note1 Tim hasAuthor <owl:ObjectProperty rdf:ID=“isAuthorFrom”> <owl:inverseOf rdf:resource=“#hasAuthor”> </owl:ObjectProperty> isAuthorFrom Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
Ontology (described in OWL) • OWL-constructions • Class • DatatypeProperty • subClassOf • Individual • … DatatypeProperty Birth date Class: Person subClassOf Class: Scientist “Joseph Plateau” Individual Birth date “14/10/1801” Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
Semantisch Web • SPARQL Protocol And RDF Query Language (SPARQL) • SQL like language for RDF • Example: search all texts of Tim • SELECT ?x WHERE ?x hasAuthor Tim Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
Why PREMIS OWL? Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
Why PREMIS OWL? • Changing Technologies World Wide Web Semantic Web XML RDF, RDFS and OWL Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
Semantic Web Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
Why PREMIS OWL? • Data model of PREMIS: Dynamically relating the Five entities to each other. XML: identifiers are used for modelling the relations. directed and not bidirectional! OWL: resources are identified by a URI direct relations between the entitities (bidirectional by using inverse relations) Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
Design Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
Design • Design decisions: • Stick as close as possible to the PREMIS 2.0 Data Dictionary. • No information loss when migrating PREMIS XML PREMIS OWL Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
Design • Changes: • Every XML wrapper has become a class. • Object has 3 subclasses: File, Bitstream, Representation. • Relations between the entities. • Linking to SKOS vocabularies. Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
Design • Object has 3 subclasses: File, Bitstream, Representation Subclasses based on the objectCategory property (“Bitstream”, “File”, “Representation”) Object Bitstream File Representation Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
Design • Relations between the entities: • Every entity has become a class. Every entity has a URI. No need for using the entities’ identifiers for relating them. This URI is used for relating the different entities. object properties and their inverse properties Object Event Identifiers Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
Design • Relations between the entities: • Every entity has become a class. Every entity has a URI. No need for using the entities’ identifiers for relating them. This URI is used for relating the different entities. object properties and their inverse properties Object Event Identifiers Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
Design • Linking to SKOS vocabularies: • event types vocabulary (eventType) • preservation level role vocabulary (preservationLevelRole) • message digest algorithm vocabulary (messageDigestAlgorithm) Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
Example Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
Example Based on the louis example: http://www.loc.gov/standards/premis/louis-2-0.xml PREMIS OWL example (serialised in N3 notation): https://docs.google.com/leaf?id=0BxtLo-HRghbvZWFjZmMwN2MtNTMyZS00NzY3LThmNzktMzMwYmFhZGM1N2Yx&sort=name&layout=list&num=50 Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
Example Mets Tiff image 1 Tiff Image 2 Validation Validation Ingestion Ingestion Migration Migration JPEG image 1 JPEG Image 2 Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL
Conclusion • Ternary relations remain problematic in OWL identifiers • Publication of the provenance information is not the primary concern of PREMIS OWL. • PREMIS = provenance metadata + technical metadata + rights metadata • Provenance metadata will become more important in the future. There are provenance models much more suited for interoperability and publication on het Web. • W3C Provenance Incubator Group • PREMIS OWL: http://mulitmedialab.elis.ugent.be/users/samcoppe/ontologies/Premis/premis.owl Sam Coppens @iPres2010 PREMIS Implementation Fair: PREMIS OWL